![Steven Rostedt](/assets/img/avatar_default.png)
When DYNAMIC_FTRACE is enabled and we use the C version of recordmcount, all objects are run through the recordmcount program to create a separate section that stores all the callers of mcount. The build process has a special file: scripts/mod/empty.o. This is built from empty.c which is literally an empty file (except for a single comment). This file is used to find information about the target elf format, like endianness and word size. The problem comes up when we need to build recordmcount. The build process requires that empty.o is built first. The build rules for empty.o will try to execute recordmcount on the empty.o file. We get an error that recordmcount does not exist. To avoid this recursion, the build file will skip running recordmcount if the file that it is building is script/mod/empty.o. [ extra comment Suggested-by: Sam Ravnborg <sam@ravnborg.org> ] Reported-by: Ingo Molnar <mingo@elte.hu> Tested-by: Ingo Molnar <mingo@elte.hu> Cc: Michal Marek <mmarek@suse.cz> Cc: linux-kbuild@vger.kernel.org Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
405 lines
12 KiB
Makefile
405 lines
12 KiB
Makefile
# ==========================================================================
|
|
# Building
|
|
# ==========================================================================
|
|
|
|
src := $(obj)
|
|
|
|
PHONY := __build
|
|
__build:
|
|
|
|
# Init all relevant variables used in kbuild files so
|
|
# 1) they have correct type
|
|
# 2) they do not inherit any value from the environment
|
|
obj-y :=
|
|
obj-m :=
|
|
lib-y :=
|
|
lib-m :=
|
|
always :=
|
|
targets :=
|
|
subdir-y :=
|
|
subdir-m :=
|
|
EXTRA_AFLAGS :=
|
|
EXTRA_CFLAGS :=
|
|
EXTRA_CPPFLAGS :=
|
|
EXTRA_LDFLAGS :=
|
|
asflags-y :=
|
|
ccflags-y :=
|
|
cppflags-y :=
|
|
ldflags-y :=
|
|
|
|
subdir-asflags-y :=
|
|
subdir-ccflags-y :=
|
|
|
|
# Read auto.conf if it exists, otherwise ignore
|
|
-include include/config/auto.conf
|
|
|
|
include scripts/Kbuild.include
|
|
|
|
# For backward compatibility check that these variables do not change
|
|
save-cflags := $(CFLAGS)
|
|
|
|
# The filename Kbuild has precedence over Makefile
|
|
kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
|
|
kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
|
|
include $(kbuild-file)
|
|
|
|
# If the save-* variables changed error out
|
|
ifeq ($(KBUILD_NOPEDANTIC),)
|
|
ifneq ("$(save-cflags)","$(CFLAGS)")
|
|
$(error CFLAGS was changed in "$(kbuild-file)". Fix it to use EXTRA_CFLAGS)
|
|
endif
|
|
endif
|
|
include scripts/Makefile.lib
|
|
|
|
ifdef host-progs
|
|
ifneq ($(hostprogs-y),$(host-progs))
|
|
$(warning kbuild: $(obj)/Makefile - Usage of host-progs is deprecated. Please replace with hostprogs-y!)
|
|
hostprogs-y += $(host-progs)
|
|
endif
|
|
endif
|
|
|
|
# Do not include host rules unless needed
|
|
ifneq ($(hostprogs-y)$(hostprogs-m),)
|
|
include scripts/Makefile.host
|
|
endif
|
|
|
|
ifneq ($(KBUILD_SRC),)
|
|
# Create output directory if not already present
|
|
_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
|
|
|
|
# Create directories for object files if directory does not exist
|
|
# Needed when obj-y := dir/file.o syntax is used
|
|
_dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))
|
|
endif
|
|
|
|
ifndef obj
|
|
$(warning kbuild: Makefile.build is included improperly)
|
|
endif
|
|
|
|
# ===========================================================================
|
|
|
|
ifneq ($(strip $(lib-y) $(lib-m) $(lib-n) $(lib-)),)
|
|
lib-target := $(obj)/lib.a
|
|
endif
|
|
|
|
ifneq ($(strip $(obj-y) $(obj-m) $(obj-n) $(obj-) $(subdir-m) $(lib-target)),)
|
|
builtin-target := $(obj)/built-in.o
|
|
endif
|
|
|
|
modorder-target := $(obj)/modules.order
|
|
|
|
# We keep a list of all modules in $(MODVERDIR)
|
|
|
|
__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
|
|
$(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
|
|
$(subdir-ym) $(always)
|
|
@:
|
|
|
|
# Linus' kernel sanity checking tool
|
|
ifneq ($(KBUILD_CHECKSRC),0)
|
|
ifeq ($(KBUILD_CHECKSRC),2)
|
|
quiet_cmd_force_checksrc = CHECK $<
|
|
cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
|
|
else
|
|
quiet_cmd_checksrc = CHECK $<
|
|
cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
|
|
endif
|
|
endif
|
|
|
|
# Do section mismatch analysis for each module/built-in.o
|
|
ifdef CONFIG_DEBUG_SECTION_MISMATCH
|
|
cmd_secanalysis = ; scripts/mod/modpost $@
|
|
endif
|
|
|
|
# Compile C sources (.c)
|
|
# ---------------------------------------------------------------------------
|
|
|
|
# Default is built-in, unless we know otherwise
|
|
modkern_cflags = \
|
|
$(if $(part-of-module), \
|
|
$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
|
|
$(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
|
|
quiet_modtag := $(empty) $(empty)
|
|
|
|
$(real-objs-m) : part-of-module := y
|
|
$(real-objs-m:.o=.i) : part-of-module := y
|
|
$(real-objs-m:.o=.s) : part-of-module := y
|
|
$(real-objs-m:.o=.lst): part-of-module := y
|
|
|
|
$(real-objs-m) : quiet_modtag := [M]
|
|
$(real-objs-m:.o=.i) : quiet_modtag := [M]
|
|
$(real-objs-m:.o=.s) : quiet_modtag := [M]
|
|
$(real-objs-m:.o=.lst): quiet_modtag := [M]
|
|
|
|
$(obj-m) : quiet_modtag := [M]
|
|
|
|
# Default for not multi-part modules
|
|
modname = $(basetarget)
|
|
|
|
$(multi-objs-m) : modname = $(modname-multi)
|
|
$(multi-objs-m:.o=.i) : modname = $(modname-multi)
|
|
$(multi-objs-m:.o=.s) : modname = $(modname-multi)
|
|
$(multi-objs-m:.o=.lst) : modname = $(modname-multi)
|
|
$(multi-objs-y) : modname = $(modname-multi)
|
|
$(multi-objs-y:.o=.i) : modname = $(modname-multi)
|
|
$(multi-objs-y:.o=.s) : modname = $(modname-multi)
|
|
$(multi-objs-y:.o=.lst) : modname = $(modname-multi)
|
|
|
|
quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
|
|
cmd_cc_s_c = $(CC) $(c_flags) -fverbose-asm -S -o $@ $<
|
|
|
|
$(obj)/%.s: $(src)/%.c FORCE
|
|
$(call if_changed_dep,cc_s_c)
|
|
|
|
quiet_cmd_cc_i_c = CPP $(quiet_modtag) $@
|
|
cmd_cc_i_c = $(CPP) $(c_flags) -o $@ $<
|
|
|
|
$(obj)/%.i: $(src)/%.c FORCE
|
|
$(call if_changed_dep,cc_i_c)
|
|
|
|
cmd_gensymtypes = \
|
|
$(CPP) -D__GENKSYMS__ $(c_flags) $< | \
|
|
$(GENKSYMS) $(if $(1), -T $(2)) -a $(ARCH) \
|
|
$(if $(KBUILD_PRESERVE),-p) \
|
|
-r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
|
|
|
|
quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
|
|
cmd_cc_symtypes_c = \
|
|
set -e; \
|
|
$(call cmd_gensymtypes,true,$@) >/dev/null; \
|
|
test -s $@ || rm -f $@
|
|
|
|
$(obj)/%.symtypes : $(src)/%.c FORCE
|
|
$(call cmd,cc_symtypes_c)
|
|
|
|
# C (.c) files
|
|
# The C file is compiled and updated dependency information is generated.
|
|
# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
|
|
|
|
quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
|
|
|
|
ifndef CONFIG_MODVERSIONS
|
|
cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
|
|
|
|
else
|
|
# When module versioning is enabled the following steps are executed:
|
|
# o compile a .tmp_<file>.o from <file>.c
|
|
# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
|
|
# not export symbols, we just rename .tmp_<file>.o to <file>.o and
|
|
# are done.
|
|
# o otherwise, we calculate symbol versions using the good old
|
|
# genksyms on the preprocessed source and postprocess them in a way
|
|
# that they are usable as a linker script
|
|
# o generate <file>.o from .tmp_<file>.o using the linker to
|
|
# replace the unresolved symbols __crc_exported_symbol with
|
|
# the actual value of the checksum generated by genksyms
|
|
|
|
cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
|
|
cmd_modversions = \
|
|
if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
|
|
$(call cmd_gensymtypes,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
|
|
> $(@D)/.tmp_$(@F:.o=.ver); \
|
|
\
|
|
$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
|
|
-T $(@D)/.tmp_$(@F:.o=.ver); \
|
|
rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
|
|
else \
|
|
mv -f $(@D)/.tmp_$(@F) $@; \
|
|
fi;
|
|
endif
|
|
|
|
ifdef CONFIG_FTRACE_MCOUNT_RECORD
|
|
ifdef BUILD_C_RECORDMCOUNT
|
|
# Due to recursion, we must skip empty.o.
|
|
# The empty.o file is created in the make process in order to determine
|
|
# the target endianness and word size. It is made before all other C
|
|
# files, including recordmcount.
|
|
cmd_record_mcount = if [ $(@) != "scripts/mod/empty.o" ]; then \
|
|
$(objtree)/scripts/recordmcount "$(@)"; \
|
|
fi;
|
|
else
|
|
cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
|
|
"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
|
|
"$(if $(CONFIG_64BIT),64,32)" \
|
|
"$(OBJDUMP)" "$(OBJCOPY)" "$(CC)" "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
|
|
"$(if $(part-of-module),1,0)" "$(@)";
|
|
endif
|
|
endif
|
|
|
|
define rule_cc_o_c
|
|
$(call echo-cmd,checksrc) $(cmd_checksrc) \
|
|
$(call echo-cmd,cc_o_c) $(cmd_cc_o_c); \
|
|
$(cmd_modversions) \
|
|
$(call echo-cmd,record_mcount) \
|
|
$(cmd_record_mcount) \
|
|
scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' > \
|
|
$(dot-target).tmp; \
|
|
rm -f $(depfile); \
|
|
mv -f $(dot-target).tmp $(dot-target).cmd
|
|
endef
|
|
|
|
# Built-in and composite module parts
|
|
$(obj)/%.o: $(src)/%.c FORCE
|
|
$(call cmd,force_checksrc)
|
|
$(call if_changed_rule,cc_o_c)
|
|
|
|
# Single-part modules are special since we need to mark them in $(MODVERDIR)
|
|
|
|
$(single-used-m): $(obj)/%.o: $(src)/%.c FORCE
|
|
$(call cmd,force_checksrc)
|
|
$(call if_changed_rule,cc_o_c)
|
|
@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
|
|
|
|
quiet_cmd_cc_lst_c = MKLST $@
|
|
cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
|
|
$(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
|
|
System.map $(OBJDUMP) > $@
|
|
|
|
$(obj)/%.lst: $(src)/%.c FORCE
|
|
$(call if_changed_dep,cc_lst_c)
|
|
|
|
# Compile assembler sources (.S)
|
|
# ---------------------------------------------------------------------------
|
|
|
|
modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
|
|
|
|
$(real-objs-m) : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
|
|
$(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
|
|
|
|
quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
|
|
cmd_as_s_S = $(CPP) $(a_flags) -o $@ $<
|
|
|
|
$(obj)/%.s: $(src)/%.S FORCE
|
|
$(call if_changed_dep,as_s_S)
|
|
|
|
quiet_cmd_as_o_S = AS $(quiet_modtag) $@
|
|
cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
|
|
|
|
$(obj)/%.o: $(src)/%.S FORCE
|
|
$(call if_changed_dep,as_o_S)
|
|
|
|
targets += $(real-objs-y) $(real-objs-m) $(lib-y)
|
|
targets += $(extra-y) $(MAKECMDGOALS) $(always)
|
|
|
|
# Linker scripts preprocessor (.lds.S -> .lds)
|
|
# ---------------------------------------------------------------------------
|
|
quiet_cmd_cpp_lds_S = LDS $@
|
|
cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -C -U$(ARCH) \
|
|
-D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
|
|
|
|
$(obj)/%.lds: $(src)/%.lds.S FORCE
|
|
$(call if_changed_dep,cpp_lds_S)
|
|
|
|
# Build the compiled-in targets
|
|
# ---------------------------------------------------------------------------
|
|
|
|
# To build objects in subdirs, we need to descend into the directories
|
|
$(sort $(subdir-obj-y)): $(subdir-ym) ;
|
|
|
|
#
|
|
# Rule to compile a set of .o files into one .o file
|
|
#
|
|
ifdef builtin-target
|
|
quiet_cmd_link_o_target = LD $@
|
|
# If the list of objects to link is empty, just create an empty built-in.o
|
|
cmd_link_o_target = $(if $(strip $(obj-y)),\
|
|
$(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \
|
|
$(cmd_secanalysis),\
|
|
rm -f $@; $(AR) rcs $@)
|
|
|
|
$(builtin-target): $(obj-y) FORCE
|
|
$(call if_changed,link_o_target)
|
|
|
|
targets += $(builtin-target)
|
|
endif # builtin-target
|
|
|
|
#
|
|
# Rule to create modules.order file
|
|
#
|
|
# Create commands to either record .ko file or cat modules.order from
|
|
# a subdirectory
|
|
modorder-cmds = \
|
|
$(foreach m, $(modorder), \
|
|
$(if $(filter %/modules.order, $m), \
|
|
cat $m;, echo kernel/$m;))
|
|
|
|
$(modorder-target): $(subdir-ym) FORCE
|
|
$(Q)(cat /dev/null; $(modorder-cmds)) > $@
|
|
|
|
#
|
|
# Rule to compile a set of .o files into one .a file
|
|
#
|
|
ifdef lib-target
|
|
quiet_cmd_link_l_target = AR $@
|
|
cmd_link_l_target = rm -f $@; $(AR) rcs $@ $(lib-y)
|
|
|
|
$(lib-target): $(lib-y) FORCE
|
|
$(call if_changed,link_l_target)
|
|
|
|
targets += $(lib-target)
|
|
endif
|
|
|
|
#
|
|
# Rule to link composite objects
|
|
#
|
|
# Composite objects are specified in kbuild makefile as follows:
|
|
# <composite-object>-objs := <list of .o files>
|
|
# or
|
|
# <composite-object>-y := <list of .o files>
|
|
link_multi_deps = \
|
|
$(filter $(addprefix $(obj)/, \
|
|
$($(subst $(obj)/,,$(@:.o=-objs))) \
|
|
$($(subst $(obj)/,,$(@:.o=-y)))), $^)
|
|
|
|
quiet_cmd_link_multi-y = LD $@
|
|
cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
|
|
|
|
quiet_cmd_link_multi-m = LD [M] $@
|
|
cmd_link_multi-m = $(cmd_link_multi-y)
|
|
|
|
# We would rather have a list of rules like
|
|
# foo.o: $(foo-objs)
|
|
# but that's not so easy, so we rather make all composite objects depend
|
|
# on the set of all their parts
|
|
$(multi-used-y) : %.o: $(multi-objs-y) FORCE
|
|
$(call if_changed,link_multi-y)
|
|
|
|
$(multi-used-m) : %.o: $(multi-objs-m) FORCE
|
|
$(call if_changed,link_multi-m)
|
|
@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
|
|
|
|
targets += $(multi-used-y) $(multi-used-m)
|
|
|
|
|
|
# Descending
|
|
# ---------------------------------------------------------------------------
|
|
|
|
PHONY += $(subdir-ym)
|
|
$(subdir-ym):
|
|
$(Q)$(MAKE) $(build)=$@
|
|
|
|
# Add FORCE to the prequisites of a target to force it to be always rebuilt.
|
|
# ---------------------------------------------------------------------------
|
|
|
|
PHONY += FORCE
|
|
|
|
FORCE:
|
|
|
|
# Read all saved command lines and dependencies for the $(targets) we
|
|
# may be building above, using $(if_changed{,_dep}). As an
|
|
# optimization, we don't need to read them if the target does not
|
|
# exist, we will rebuild anyway in that case.
|
|
|
|
targets := $(wildcard $(sort $(targets)))
|
|
cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
|
|
|
|
ifneq ($(cmd_files),)
|
|
include $(cmd_files)
|
|
endif
|
|
|
|
|
|
# Declare the contents of the .PHONY variable as phony. We keep that
|
|
# information in a variable se we can use it in if_changed and friends.
|
|
|
|
.PHONY: $(PHONY)
|